Stability discussion and application study of pseudo-corner models

Abstract

Accurate plastic flow modelling under complex working conditions is crucial for metal deformation simulations. Recently, some advanced pseudo-corner models have been developed to describe corner effects and analyze strain localization problems. The present work consists of three parts. The first part discusses the intrinsic stability of the pseudo-corner model class, which forms the premise of application analysis. The second part applies the pseudo-corner models and the associated flow rule (AFR) to buckling onset estimation, plastic post-buckling analysis and shear band analysis. The experimental conditions are strictly reproduced and the optimal model parameters are determined. The results reveal that the pseudo-corner models and AFR are indistinguishable in the buckling onset estimation. AFR overestimates the post-buckling strength of circular tubes under axial compression, and cannot reproduce the shear band development during sheet bending; while the pseudo-corner models have better prediction performance in both scenarios. The results also suggest that the parameter values of pseudo-corner models are apparently inconsistent in the above two types of problems. Then in the third part, two representative influencing factors including strain gradient plasticity and initial imperfections are discussed, and this inconsistency is finally attributed to the shortwave surface defect which however is usually neglected by previous studies.